fix(core): file asset publishing role not used in cdk diff to upload large templates

[sumupitchayan]

Closes #29936

Reason for this change

When running cdk diff on larger templates, the CDK needs to upload the diff template to S3 to create the ChangeSet. However, the CLI is currently not using the the file asset publishing role to do so and is instead using the IAM user/role that is configured by the user in the CLI - this means that if the user/role lacks S3 permissions then the AccessDenied error is thrown and users cannot see a full diff.

Description of changes

This PR ensures that the FileAssetPublishingRole is used by cdk diff to upload assets to S3 before creating a ChangeSet by:

• Deleting the makeBodyParameterAndUpload function which was using the deprecated publishAssets function from deployments.ts
• Building and Publishing the template file assets inside the uploadBodyParameterAndCreateChangeSet function within cloudformation.ts instead

Description of how you validated changes

Integ test that deploys a simple CDK app with a single IAM role, then runs cdk diff on a large template change adding 200 IAM roles. I asserted that the logs did not contain the S3 access denied permissions errors, and also contained a statement for assuming the file publishing role. Reused the CDK app for the integ test from this PR by @sakurai-ryo which tried fixing this issue by adding another Bootstrap role (which we decided against).

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

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[rix0rrr]

Deleting the broken makeBodyParameterAndUpload function which wasn't actually uploading anything to S3.

This is not a correct statement. It definitely was uploading things to S3.

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➡️ PR build request submitted to test-main-pipeline ⬅️

A maintainer must now check the pipeline and add the pr-linter/cli-integ-tested label once the pipeline succeeds.

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AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: e0dc88c
• Result: SUCCEEDED
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